In conventional medical practice there exists an ultrasonic diagnosis apparatus that repeatedly transmits an ultrasonic pulse into a live body from an ultrasonic transducer, then receives an echo of the ultrasonic pulse reflected from the live body by the same or separately equipped ultrasonic transducer, and then gradually shifts the direction of transmission and reception of the ultrasonic pulse, thereby displaying information collected from a plurality of directions within the live body as a visible ultrasonic tomography image.
The ultrasonic transducers used for such an ultrasonic diagnosis apparatus or the like include an array type ultrasonic transducer employing an electronic scanning system that arrays a plurality of piezoelectric elements regularly. This ultrasonic transducer includes a radial array type that arrays a plurality of piezoelectric elements in a cylindrical arrangement, a convex array type that arrays them in roughly a partially cylindrical arrangement, and a linear array type that arrays them in a plate arrangement.
The radial array type ultrasonic transducer has conventionally been produced by sequentially adhering, on a support member formed by a flexible thin plate which has a damper effect, for example, a piezoelectric plate, made of lead zirconate titanate for example, and an acoustic matching layer. This adhering is followed by forming cut-in grooves, leaving the support member in the lower layer uncut, of predetermined pitches perpendicular to the longitudinal direction by a cutting means for constituting an transducer array having a large number of ultrasonic transducers, and by adhering the back surface of the support member structuring the transducer array onto the circumference of a damper member-cum-fix member (also called “backing member”) whose cross-section is circular (for an example, refer to patent document 1).
An ultrasonic wave probe has conventionally been produced by equipping both surfaces of a piezoelectric element respectively with an acoustic matching layer and a backside load member made of a deformable material and cut-in grooves are formed at predetermined intervals by a cutting means, starting from the side of the acoustic matching layer down to a part of the backside load member. The backside load member is fixed with an adhesive onto the outer surface of a curvature member that is formed to a desired curvature (for an example, refer to patent document 2).
There is also another ultrasonic array transducer configured by putting a backing member frame on the inside of an acoustic lens, mounting a cable harness board on the inside of the backing member frame, and filling the circumference thereof with the backing member (for an example, refer to patent document 3).
Meanwhile, the electronic scanning type ultrasonic transducer is equipped on a part of an endoscope that is inserted into an abdomen, the use of which makes it possible to extract a clear image of deep organs such as digestive canal walls and the pancreas, gall bladder, etc., with good image quality and without being ill influenced by abdominal gases or bones. The electronic scanning type ultrasonic transducer is constituted by no less than several tens of elements and a number of coaxial cables for transmission and reception equivalent to the number of elements. When connecting an electrode of each element of the electronic scanning type ultrasonic transducer to a signal transmission/reception use coaxial cable, a common method is to solder a core lead of the coaxial cable to a signal electrode of each element and to solder a shield wire of the coaxial cable to a ground electrode of each element.
Electronic scanning type ultrasonic transducers such as that described above that have been utilized for an endoscope include convex types, linear types, and radial types, as noted above. The radial type is for transmitting and receiving an ultrasonic beam around a circumference and is categorized into two systems, a mechanical radial scanning system transmitting and receiving an ultrasonic beam radially by rotating the transducers and an electronic radial scanning system transmitting and receiving an ultrasonic beam radially by arraying a plurality of piezoelectric elements on the circumference of a cylinder and electronically controlling them (for an example, refer to patent document 4).
In the case of producing an electronic radial type ultrasonic transducer, a cylindrical shape must be produced in a manner in which both end surfaces of ultrasonic transducer plates that have been divided into a plurality of ultrasonic transducers (i.e., ultrasonic transducer elements) are aligned, as disclosed by patent document 4.
FIG. 1 is a diagram showing a conventional ultrasound endoscope apparatus.
The ultrasound endoscope apparatus 1000 shown in FIG. 1 comprises a connection part 1010, an operation part 1020, and an insertion part 1030 that comprises a head part 1040.
The connection part 1010 is connected to a display apparatus comprising, for example, a display and/or other such device(s) for displaying images or other such things photographed by an ultra compact camera or other such device equipped on the head part 1040.
The operation part 1020 performs curving operations of the insertion part 1030 in the left, right, up and down directions via operation by a user, for example.
The head part 1040 is equipped with a radial system ultrasonic transducer array constituted by, in addition to the ultra compact camera, a plurality of ultrasonic transducers being lined up continuously in a circular pattern around the insertion axis as the center; a selected ultrasonic transducer from among the plurality thereof of the radial system ultrasonic transducer array transmits or receives an ultrasonic wave. The ultrasonic wave received by the ultrasonic transducer array is converted into an electric signal for being displayed on the display or other such device as an image.
FIG. 2 is an enlarged diagram of the dotted line frame H shown in FIG. 1.
As shown in FIG. 2, the head part 1040 comprises a camera part 1110 equipped with an ultra compact camera, illumination element, et cetera, and an ultrasonic wave part 1111 to be equipped with the radial system ultrasonic transducer array and/or other such device.
FIG. 3 is a diagram exemplifying an ultrasonic transducer array.
The ultrasonic transducer array 1120 shown in FIG. 3 comprises a piezoelectric element 1121, a first acoustic matching layer 1122 and a second acoustic matching layer 1123.
The piezoelectric element 1121, first acoustic matching layer 1122 and second acoustic matching layer 1123 are divided into a plurality thereof by commonly featured grooves, resulting in the constitution of the plurality of ultrasonic transducers. Note that the groove featured commonly for the piezoelectric element 1121, first acoustic matching layer 1122 and second acoustic matching layer 1123 is extended from the upper face of the piezoelectric element 1121 to a part of the second acoustic matching layer 1123 so that the individual ultrasonic transducers are connected to one another by the second acoustic matching layer 1123 according to this comprisal as shown in FIG. 3.
The individual grooves are equipped with division members 1124 (i.e., 1124-1, 1124-2, 1124-3, 1124-4, 1124-5 and so on), respectively. The division members 1124 are constituted by a resin or by particles attenuating an ultrasonic wave, and are constructed by the aforementioned material filling in the grooves that are featured commonly for the piezoelectric element 1121, first acoustic matching layer 1122 and second acoustic matching layer 1123; this is followed by the material being solidified (for an example, refer to patent document 5).
As to the ultrasonic transducer array 1120, the end surfaces in the direction perpendicular to the longitudinal direction of the ultrasonic transducer array 1120 are connected with one another from the state shown in FIG. 3, thereby constructing the radial system ultrasonic transducer array.
FIG. 4 is a diagram showing a constructed radial system ultrasonic transducer array from the ultrasonic transducer array 1120 shown in FIG. 3.
The inside of an opening part of the radial system ultrasonic transducer array 1120 shown in FIG. 4 is equipped with a roughly donut-shaped frame member 1130 that retains the state of the individual ultrasonic transducers of the ultrasonic transducer array 1120 being formed in a circular pattern.
There already exists such a case in which the frame member 1130 is used to retain the form of individual ultrasonic transducers of the ultrasonic transducer array 1120 (for an example, refer to patent document 3).
The electronic radial type ultrasonic transducer is able to perform scans in 360 degrees, and therefore the scan intervals are desirably uniform across all directions.
In order to form the ultrasonic transducer arraying the ultrasonic transducer elements on a plane into a circular shape as described above, however, a side face on one end must be matched with that on the other end in order to roll up the flat-formed ultrasonic transducer into a cylindrical shape, resulting in the creation of a joint part for the electronic radial type ultrasonic transducer.
As shown in FIG. 5, the conventional electronic radial type ultrasonic transducer ends up with a different interval between the adjacent ultrasonic transducer elements in the place at which the ends are joined (joint 2010) in an ultrasonic transducer plate 2000 that is rolled up into a cylindrical shape, and this causes an ill influence on images obtained from the ultrasonic transducer elements encompassing the joint 2010.
Such a joint is unique to electronic radial type transducers and is not seen in the convex type or linear type transducers; therefore special care has conventionally been required in the handling of regions corresponding to the joint when photographing the interior of an abdomen with an ultrasound endoscope that uses an electronic radial type ultrasonic transducer.
The electronic radial type ultrasonic transducer used for an ultrasound endoscope is now being configured to have the outer diameter of the transducer be around 10 mm so that a variation of a few tens of micrometers alters the angle and interval of the adjacent transducer. This causes a significant ill influence on image quality when compared to large scale ultrasonic transducers such as sonar in which a displacement of a few tens of micrometers at a joint is not significant.
A backing member usually uses a soft resin for retaining a damping effect. However, if the joint is adhered with the backing member, durability is undermined when performing sterilization treatment via chemicals or heating. As such, connection of a joint with the backing member material results in varying characteristics and leads to reduced durability due to the use of a flexible material.
Also, in either of the radial system ultrasonic transducer arrays 1120 shown in FIG. 4, the convex system ultrasonic transducer array or the linear system ultrasonic transducer array, a predefined ultrasonic transducer needs to be identified when producing, inspecting or repairing the ultrasonic transducer array.
For the convex system ultrasonic transducer array and the linear system ultrasonic transducer array, a predefined ultrasonic transducer can be identified by registering information on a function of the nth ultrasonic transducer from the one at an end in advance and counting the ultrasonic transducers in sequence from the one at the end.
In an ultrasonic transducer array symmetrically formed for obtaining a good acoustic characteristics such as the radial system ultrasonic transducer array 1120 shown in FIG. 4, the individual ultrasonic transducers are formed into a circular pattern by mutually connecting the ultrasonic transducers at both ends, making it difficult to identify ultrasonic transducers at the ends; this results in a difficulty in identifying a specific ultrasonic transducer.
Also, in the convex system ultrasonic transducer array and linear system ultrasonic transducer array, if an ultrasonic transducer array used for an ultrasound endoscope apparatus is very small, it is difficult to count the ultrasonic transducers and hence difficult to identify a predefined ultrasonic transducer.
Also, the ultrasonic transducer formed by fixing a flexible support member to a damper member with an adhesive, such as the ultrasonic probe noted in patent document 1, has been faced with the possibility of occurrences of performance problems such as an elongated pulse width caused by the adhesive layer being placed in between the support member and the damper member.
Also, in the production method for the ultrasonic wave probe noted in patent document 2, a flexible or deformable elastic member is curved and is fixed to a damper member or curved member with an adhesive, thereby forming a prescribed feature. Because of this, there is a possibility that a residual stress in the elastic member will cause a broken electrical connection or other such failure.
Furthermore, when fixing a soft member with an adhesive, the thickness of the adhesive layer varies and the form of the member cannot be maintained at a high accuracy; this is different from the case of adhering hard members to each other, and therefore it has been difficult to obtain the desired accuracy of the form.
Requirements for the backing member frame include high form accuracy, insulation, the capability of adding a conductor pattern and thermal resistance against heat from soldering in cases in which there is a connection to a lead wire, and other properties. However, common board materials such as glass epoxy board used for the usage described above have been faced with difficulties in improving the accuracy of the machining process because of minute changes in form as a result of the glass fiber coming off the resin at an edge part that is being processed for a feature.
In addition, polyimide has a low rigidity and a low adhesive property, and is thus faced with the problem of being unsuitable for use for a frame.
In consideration of the above described problems, a purpose of the present invention is to provide an electronic radial type ultrasonic transducer that makes all of the environment uniform in relation to a material and in relation to the interval between ultrasonic transducer elements.
Another purpose of the present invention is to provide an ultrasonic transducer array that enables the easy identification of a predefined ultrasonic transducer no matter what system it is categorized as.
Yet another purpose of the present invention is to provide an ultrasonic transducer with a high reliability and strength that is capable of obtaining a good ultrasonic image by preventing occurrences of failure that are due to residual stress and by the highly accurate arraying of divided piezoelectric elements via the use of polyphenylether (PPE) as a frame material. PPE has the characteristics of high thermal resistance, good processability, and good retainability of external features.
Patent document 1: Laid-Open Japanese Patent Application Publication No. H02-271839
Patent document 2: Japanese Registered Patent No. 2502685
Patent document 3: Laid-Open Japanese Patent Application Publication No. 2002-224104
Patent document 4: Japanese Registered Patent No. Sho 63-14623
Patent document 5: Laid-Open Japanese Patent Application Publication No. H10-285695